1. Field of the Invention
The present invention relates to a sample analyzing method and a sample analyzing apparatus that measure optical characteristics of a sample, in which a multi-layer structure deposited on a transparent substrate is covered with a cover material at a distance, by using a measuring unit for irradiating a polarized light and then analyze the characteristics of the respective deposited layers of the sample, in accordance with the model corresponding to the sample and the measured result of the measuring unit.
Also, the present invention relates to a manufacturing method of an organic EL element, which is formed from a plurality of layers, step by step, in a plurality of film deposition chambers, and manufacturing equipment used in the method.
Also, the present invention relates to a sample analyzing method and a sample analyzing apparatus that measure the optical characteristics of a sample, in which multi-layer structure is deposited on a transparent substrate are covered with a cover material, by using a measuring unit for irradiating a polarized light and then analyze the characteristics of the respective deposited layers of the sample, in accordance with the model corresponding to the sample and the measured result of the measuring unit using a computer-readable recording medium, to enable the sample analyzing apparatus function.
2. Description of the Prior Art
Conventionally, in order to analyze the characteristics (a refractive index of a film, an extinction coefficient, a film thickness and the like) of a sample having a film, a measuring unit for measuring by irradiating a polarized light such as a polarimeter and an ellipsometer was used. For example, in the ellipsometer, the polarized light is inputted to the sample, and the changes in the polarization states of an incident light and reflected light are measured, thereby calculating an amplitude ratio (Ψ psi) and a phase difference (Δ delta) as shown in FIG. 1A. It is impossible to determine unique combination of a film thickness (d), a refractive index (n), an extinction coefficient (k) of the film from the amplitude ratio and phase difference obtained by the ellipsometer. Therefore, in accordance with the assumption content (substrate type, a film thickness and the like) for the items of an analysis target sample inputted by a user, a model based on the sample structure is established, and the model and the measurement results of the ellipsometer are used to analyze the sample.
The specific analyzing procedure is as follows. At first, the amplitude ratio and the phase difference that are calculated from the model by a theoretical calculation and the amplitude ratio and the phase difference the measured by the ellipsometer are compared. Then, in such a way that the difference between them becomes minimal, a process for changing parameters of a dispersion formula related to the model and the film thickness in the model and the like is carried out (referred to as a fitting). The difference between them is usually calculated by the calculation that uses a least squares method. When the result obtained by the least squares method through the fitting is judged to become small to a certain degree, the refractive index and the extinction coefficient of the film are calculated from the values of the parameters in the dispersion formula at that time, and the film thickness at that time is selected as the film thickness of the respective layer of the sample.
Note that the construction of the model, the calculation based on the least squares method, the fitting and the like are typically carried out manually or automatically in accordance with a necessary program installed into a computer (refer to patent documents 1, 2).
[Patent Document 1] Japanese Laid Open Patent Application (JP-P 2002-340789)
[Patent Document 2] Japanese Laid Open Patent Application (JP-P 2002-340528)
An organic EL (Electroluminescence) element is a self light emitting device which has a basic multi-layer structure containing a lower electrode, several organic films, including an organic light emitting layer, and an upper electrode deposited on a substrate. Since a voltage is applied between the upper electrode and the lower electrodes, electrons are injected from a cathode side, formed on one of the electrodes into the organic layer. Holes are injected from an anode side formed on the other of electrode into the organic layer. Holes and electrodes are recombined in the organic light emitting layer, and the light is consequently emitted.
A manufacturing equipment of an organic EL element of a cluster type is known (for example, a patent document 3), as a manufacturing equipment of such an organic EL element. FIG. 2 is a schematic plan view showing the configuration of a conventional cluster type manufacturing equipment. In the drawing, 200 is the cluster type manufacturing equipment and is provided with two series of film forming cluster (apparatuses) 210, 220 and a sealing cluster 230. A substrate feeding chamber 241 is installed and linked to the film forming apparatus 210 on the feeding side, and receiving/sending chambers 242, 243 are installed and linked between the film forming apparatuses 210, 220 and the sealing cluster 230, respectively, and a discharging chamber 244 is installed and linked to the sending side of the sealing cluster 230. Feeding robots 211, 221 are placed inside the film forming apparatuses 210, 220, and a plurality of evaporating chambers 212, 213, 214, 222, 223 and 224 are installed around them. Then, inspecting chambers (for measuring the film thicknesses) 215, 225 are installed in the respective film forming apparatuses 210, 220, respectively.
A feeding robot 231 is placed also at the center of the sealing cluster 230. In the periphery thereof, a sealing substrate feeding chamber 232, an inspection chamber (for measuring a light emission characteristic) 233, a sealing chamber 234 and a spare vacuum chamber 235 are installed. Then, vacuum gates 1G are installed in the input ports of the respective evaporation chambers 212, 213, 214, 222, 223 and 224, and the output/input ports of the substrate feeding chamber 241, the receiving/sending chambers 242, 243, the sealing substrate feeding chamber 232 and the discharging chamber 244.
Here, in the film forming apparatuses 210, 220, the evaporating chambers 212, 213, 214, 222, 223 and 224 are intended to form the organic films (hole transport layers, light emitting layers (R, G and B) and electron feeding layers) and the upper electrodes, respectively. Vacuum evaporation apparatuses such as resistance heating types and the like are installed, and each of them has an evaporation source for heating and evaporating the evaporation material of each layer. An optical film thickness measuring units for actually measuring the deposited film thicknesses are installed in the inspection chambers 215, 225. Then, so as to enable the film thickness setup adjustment in the evaporating chambers in accordance with the inspection results in the inspection chambers 215, 225, the inspection chamber 215 and the respective evaporation chambers 212 to 214 or the inspection chamber 225 and the respective evaporation chambers 222 to 224 are connected through a data transmitting device (including transmission lines and transmitting/receiving apparatuses) 1P.
According to the foregoing manufacturing equipment, the substrate (ITO substrate), on which a pre-processing step and a washing operation are already performed, is fed into the substrate feeding chamber 241 and passed to the feeding robot 211 of the film forming apparatus 210. With the operation of the feeding robot 211, the evaporation is sequentially executed in the evaporating chambers 212, 213 and 214, and the film thicknesses of the deposited layers are measured in the inspecting chamber 215. The receiving/sending operation from the feeding robot 211 on the side of the film forming apparatus 210 to the feeding robot 221 on the side of the film deposition side 220 is carried out in the receiving/sending chamber 242. Then, in the film forming chamber 220, with the operation of the feeding robot 221, the evaporation is sequentially executed in the evaporating chambers 222, 223 and 224, and the film thicknesses of the deposited layers are measured in the inspecting chamber 225.
Concrete the example of the film forming step of this manufacturing equipment is disclosed, for example, the film deposition of a first color is carried out in the film forming apparatus 210, the hole transport layer that is common for each color is evaporated in the evaporating chamber 212, the light emission layer (B) is evaporated in the evaporating chamber 213, and the electron feeding layer (B) is evaporated in the evaporating chamber 214, respectively. Then, the film forming adjustment for a chromaticity compensation layer is carried out in accordance with the simulation of the light emission characteristic based on the measurement result (the measurement result in the inspecting chamber 215 is transmitted to the evaporating chamber 214, and the film thickness setting is carried out in the evaporating chamber 214). After that, the substrate is again fed into the evaporating chamber 214 or the different evaporating chamber (not shown), and in accordance with the adjusted setting film thickness, the chromaticity compensation layer composed of the electron feeding layers is formed.
After that, it is passed to the film forming apparatus 220, and the film deposition of a second color is carried out. The light emitting layer (G) is evaporated in the evaporation chamber 222. Next, the electron feeding layer (G) is evaporated in the evaporation chamber 223. After that, it is fed to the inspection chamber 225, and the deposited film thickness is measured. Then, the film forming adjustment for the chromaticity compensation layer is carried out in accordance with the simulation of the light emission characteristic based on the measurement result. After that, it is again fed into the evaporating chamber 223 or the different evaporating chamber (not shown), and the chromaticity compensation layer composed of the electron feeding layers is formed in accordance with the adjusted setting film thickness.
Then, after the upper electrode is finally evaporated in the evaporating chamber 224, the substrate is fed through the receiving/sending chamber 243 to the sealing cluster 230. In the sealing cluster 230, at first, it is fed to the inspection chamber 233, and the light emission characteristic is measured therein, and the fact that there is no chromaticity shift is checked. Then, the substrate, on which the organic films and the upper electrode are formed, and the sealing substrate fed from the sealing substrate feeding chamber 232 are both fed to the sealing chamber 234, and both of them are stuck to each other using adhesive material. An organic EL panel after the completion of the sealing is fed out through the discharging chamber 244 outside the apparatus. In addition to the manufacturing equipment of the cluster type as mentioned above, a manufacturing equipment of an in-line type where the film forming apparatus to which the evaporating chamber is linked and the sealing cluster are arranged in parallel is known.
[Patent Document 3] Japanese Laid Open Patent Application (JP-P 2005-322612)
Conventionally, in order to analyze the characteristics (the refractive index of the film, the extinction coefficient, the film thickness and the like) of the sample having the film, the polarimeter, the ellipsometer and the like have been used. For example, in the ellipsometer, the polarized light is inputted to the sample, and the changes in the polarization states of the incident light and reflected light are measured, thereby calculating the amplitude ratio (Ψ psi) and the phase difference (Δ delta). Also, only by using the amplitude ratio and phase difference calculated by the ellipsometer, from only one set for the sample, it is impossible to calculate the refractive index (n) of the film, the extinction coefficient (k) and the film thickness (d). So, in accordance with the assumption content (the kind of the substrate, the film thickness and the like) for the items of the sample of the analysis target inputted by the user, the model based on the structure of the sample is established, and the model and the measurement results of the ellipsometer are used to analyze the sample.
The specific analyzing procedure is as follows. At first, the amplitude ratio and the phase difference that are calculated from the model by the theoretical calculation and the amplitude ratio and the phase difference that are calculated by the measurement of the ellipsometer are compared. Then, in such a way that the difference between them becomes minimal, the process for changing the parameter of the dispersion formula related to the model and the film thickness of the model and the like is carried out (referred to as the fitting). The difference between them is usually calculated by the calculation that uses the least squares method. When the result obtained by the least squares method through the fitting is judged to become small to a certain degree, the refractive index of the film and the extinction coefficient are calculated from the value of the parameter in the dispersion formula at that time, and the film thickness at that time is selected as the film thickness of the film of the sample.
Note that the preparation for the model, the calculation based on the least squares method, the fitting and the like are typically manually or automatically carried out in accordance with the necessary program by using the computer (refer to patent documents 4, 5).
A technique for using the foregoing ellipsometer for measuring the film thickness of the organic EL (Electro-Luminescence) element and the like is disclosed (for example, a patent document 6). The organic EL element has the basic structure where the lower electrode, the organic layer including the organic light emission function layer, and the upper electrode are deposited on the transparent substrate.
Since the voltage is applied between the upper electrode and the lower electrode of the organic EL element, the electrons are injected from the cathode side formed on one of the upper electrode and the lower electrode into the organic layer. The holes are injected from the anode side formed on the other of the upper electrode and the lower electrode into the organic layer, and they are again coupled in the organic light emission function layer in the organic layer, and the light is consequently emitted. After the organic films and the like are formed on the transparent substrate, the cover material for covering the organic layer and the like is stuck on the transparent substrate, and the organic EL element panel is completed and shipped as a product.
[Patent Document 4] Japanese Laid Open Patent Application (JP-P 2002-340789)
[Patent Document 5] Japanese Laid Open Patent Application (JP-P 2002-340528)
[Patent Document 6] Japanese Laid Open Patent Application (JP-P 2005-322612)
In the analysis that uses the ellipsometer as mentioned above, the kinds of the samples targeted for the analysis are various, which leads to the request desired to analyze the sample having the film that is not exposed to outside, in recent years. For example, in order to research and develop materials of an organic EL (OLED: Organic Light Emitting Diode) element, to which attention is paid as a next generation display, and in order to inspect a product, it is expected to analyze the organic films of the organic EL element in accordance with the analyzing method of using the foregoing ellipsometer. In particular, it is desired to be able to check whether or not the prototype organic EL element or the manufactured organic EL element has the structure according to a design, or if the structure is not based on the design, it is desired to be able to determine which of the points are defective. Also, it is desired to be able to check how the organic EL element is chronologically changed (deteriorated).
However, the organic EL element has the structure which contains an anode, the plurality of films (organic films) and the cathode deposited on the transparent substrate such as a glass substrate, and the films are covered with a sealing cap, and the inside is vacuum-sealed, or the rare gas and the like are filled inside the sealed space. For this reason, there is a problem that the method of irradiating the light towards the multi-layer film structure existing in the sealed space and properly obtaining the reflected light and then measuring the optical characteristics of the film using the ellipsometer becomes very difficult. Thus, there is a problem that in the present situation, it is impossible to check properly whether or not the manufactured organic EL element has the structure according to the design, which of the point is defective, and the chronological change and the like.
Also, even if the light can be irradiated onto the deposited film arranged inside the sealing cap, space (gap) exists between the sealing cap and the film. For this reason, depending on the gap dimension, the irradiation of the light causes an interference pattern. If the interference pattern is generated, there are problems that it takes a very long time to measure and that the values of the amplitude ratio (Ψ) and the phase difference (Δ) which are calculated in accordance with the model have the minute amplitudes in the upper and lower directions as shown in FIG. 1B and the excellent analysis cannot be attained.
Moreover, because of the structure of the organic EL element, a plurality of reflection manners with regard to the light irradiated towards the film of the organic EL element are assumed, which results in a problem that the accurate analysis cannot be attained unless a plurality of the kinds with regard to the models to be used for the analysis are also prepared and the model corresponding to the reflection manner is suitably selected.
For example, in the case under the assumption that the light can be irradiated towards the film from the glass substrate side of the organic EL element, when the irradiated light is reflected on the boundary between the film and the gap, the plurality of reflection manners may be induced when the light is passed through the gap and reflected on the inner surface of the sealing cap. However, in such a case, the reflection manner among the foregoing plurality of reflection manners, to which the reflected light from the sample actually obtained by the ellipsometer belong, cannot be typically judged, which disables the selection of the kind of the model to be used for the analysis. For this reason, the actual analysis is required to carry out the vast amount of calculations by using all the kinds of the models so as to be able to consider all of the reflection manners and select the best calculation result from them as the analysis result. Thus, even if the organic EL element can be measured, there is a problem that the burden on the analyzing process is severe and the long time is needed until the analysis result is obtained. Note that the foregoing respective problems may occur in the case of analyzing the sample having the structure similar to the organic EL element, but other than the organic EL element. Also, even if the polarimeter is used as the measuring unit, the foregoing problems are similarly induced.
However, in the conventional manufacturing equipment, each time after the film deposition of each layer in corresponding evaporating chamber, a deposited multi-layer product is fed into the inspecting chamber, and the optical film thickness is measured, which requires the long time for the evaporation and inspection steps. Also, the deposited multi-layer product is required to be moved between the evaporating chamber and the inspecting chamber. Thus, there is a problem that the management burden of the vacuum state inside the apparatus becomes great. The optical film thickness measurement is executed in the inspecting chamber after the film deposition of each layer, thus, if an error in the film thickness exists, the film thickness adjustment for the chromaticity compensation layer is required to be carried out in the evaporating chamber in a next stage. Hence, there is a problem that the number of the steps is increased.
However, the technique noted in the patent document 6 only measures the film thickness after the film deposition of each film. Thus, there is a problem that the optical characteristic of the organic EL element panel at the shipping stage where the cover material is stuck on the transparent substrate cannot be measured. In particular, if the manufactured organic EL element panel has the structure according to the design or does not have the structure according to the design, it is desired to be able to determine which of the layers is defective. Moreover, it is required to consider the precise problem of deterioration with time of the optical characteristics of the organic EL element panel. Note that the patent document 4 and the patent document 5 do not disclose the means to solve the foregoing problems.